Temperatures are expected to climb dangerously high this week as a strong area of high pressure builds across New England.

Meteorologists say extremely hot conditions are on the horizon in Maine, with a combination of heat and humidity potentially making it feel as hot as 110 degrees.

Peak temperatures in the mid- to upper-90s are expected ahead of the Fourth of July holiday, between Wednesday and Friday.

The National Weather Service has issued an extreme heat watch for portions of southern, central and western Maine for those three days. The watch is in effect in southern portions of Oxford and Franklin counties, York County, Cumberland County, as well as Androscoggin, Kennebec, Sagahadoc and Lincoln counties.

Meteorologist Jerry Combs, who works in the weather service office in Gray, said high temperatures and humidity are expected to increase throughout the week.

Temperatures were expected to top out between the mid- to upper-80s Monday and then climb to near 90 degrees Tuesday.

Combs said temperatures will remain relatively high into the night throughout the rest of the week, which can make the stretch of heat even more dangerous.

Especially with the holiday and outdoor activities approaching, people should be cautious when spending extended periods outside, Combs said. He encouraged people to wear light-colored clothing and sunscreen and to stay hydrated. If possible, outdoor work should be delayed until the heat passes, and people should take frequent breaks in air conditioning.

Children and pets should never be left unattended in vehicles, Combs said. Meteorologists also warn that heat-related illnesses increase significantly during high heat and humidity.

The Maine Emergency Management Agency website lists open cooling centers across the state.

Portland announced that the city’s cooling center will be open at the Portland Public Library in Monument Square from 10 a.m. to 6 p.m. on Wednesday and Thursday and at the Troubh Ice Arena from 10 a.m. to 5 p.m. on Friday.

In Falmouth, three locations are open seasonally for people to cool off: the Mason-Motz Activity Center, Family Ice Arena and Falmouth Memorial Library. The Lisbon Police Department lobby is also open as needed, according to the emergency management agency.